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From "A B (JIRA)" <derby-...@db.apache.org>
Subject [jira] Created: (DERBY-402) INTERSECT/EXCEPT/UNION operators don't agree with documented behavior.
Date Wed, 29 Jun 2005 00:10:57 GMT
INTERSECT/EXCEPT/UNION operators don't agree with documented behavior.
----------------------------------------------------------------------

         Key: DERBY-402
         URL: http://issues.apache.org/jira/browse/DERBY-402
     Project: Derby
        Type: Bug
  Components: SQL  
    Versions: 10.1.1.0, 10.0.2.2    
    Reporter: A B
     Fix For: 10.2.0.0


I noticed the following two differences between what the documentation (Reference Manual)
says about UNION/INTERSECT/EXCEPT queries and what the actual Derby behavior is.  I'm filing
this issue as a single "bug" against Derby, but if it turns out later that this is really
just a documentation issue, or that these are "improvements" instead of bugs, anyone should
feel free to change the relevant fields in this issue...

1) -- p. 63 of the Reference Manual (PDF version): "SelectExpression" -> "Naming columns"

First paragraph in this section includes the following:

    When the SelectExpression appears in a UNION, INTERSECT,
    or EXCEPT operator, the names from the first SelectExpression
    are taken as the names for the columns in the result of
    the operation.

But this doesn't appear to be true.  Ex:

ij> select a from t1 union select b from t2;
1				// This "1" should be "A", according to doc.
-----------
1
2

If this behavior is intentional, then an ORDER BY clause on a UNION/INTERSECT/EXCEPT result
set can only reference the result columns by position (ex. would have to use "order by 1"
in the above query since "order by  a" doesn't work (because the name of the result column
isn't "a")).

Note that if both SelectExpressions have the same column name, then things work  differently:

ij> select a from t1 union select b as a from t2;
A				// Now it's "A" instead of "1".
-----------
1
2

So what needs to be corrected here?  The documentation or the code?

2) -- p. 133 of  the Reference Manual: "Dynamic Parameters" ->  "Where dynamic parameters
are allowed"

Number 16 says "a dynamic parameter is allowed to represent a column if it appears in a UNION,
INTERSECT, or EXCEPT expression."  But the two examples that it gives both fail:

ij> SELECT ? FROM t UNION SELECT 1 FROM t;
ERROR 42X34: There is a ? parameter in the select list.  This is not allowed.

ij> VALUES 1 UNION VALUES ?;
ERROR 42X34: There is a ? parameter in the select list.  This is not allowed.

I also tried preparing these statements using JDBC, but they failed there with the same error..

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